[dotnet] Remove System.Drawing.Common as package dependency

[nvborisenko]

This is continuation of #12777, please review that first.

Description

I think selenium is not responsible to convert images from one format to another. It is already enough for users to deal with images in png format, even it is possible to save image as file.

If user wants to convert image, then he is able to get image as bytes and use any other 3rd-party library especially designed to work with graphics.

Motivation and Context

Continue my way to reduce package dependencies.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[titusfortner]

I think where this is coming from is that Java supports:

• Base64
• Bytes
• File (stored as png)

If .NET doesn't allow saving as png in default libraries...

We can't just remove this. We can deprecate the method.
We should have a different method to return it as a Stream so a user knows they need to do something else with it.

Another option that might be nice is to move the ability to save a stream as a PNG to the support package.

[nvborisenko]

Now all users will get a warning. And those, who are really converting image to different formats, will get exception at runtime.

[titusfortner]

Please rebase on trunk and fix conflicts so I can better see what this is doing. :)

[titusfortner]

those, who are really converting image to different formats, will get exception

I think we want to do this in stages. If we are removing functionality we should mark it as obsolete for a couple releases, then remove it.

[nvborisenko]

Agree, I will prepare separate PR just to mark methods as obsolete. Keeping this one as open until we decide completely remove it.

[nvborisenko]

I think we are ready to land it.

[ckuetbach]

Two weeks for a breaking change in a minor release is somewhat annoying.

The Obsolete message was merged 22nd October and the breaking change was introduced Nov 10. (#12878)

[nvborisenko]

The obsolete message shipped with v4.14 (25 Sep) and breaking change shipped with v4.16 (06 Dec). Selenium project doesn't follow semantic versioning, sorry for inconvenience.